(a) Field of the Invention
Generally, the present invention relates to a clutch of an automatic transmission of a vehicle. More particularly, the clutch has a minimized length in order to decrease a size of an automatic transmission and increase durability thereof.
(b) Description of the Related Art
Typical automatic transmissions include a torque converter and a powertrain of a multiple speed gear mechanism connected to the torque converter. In addition, a hydraulic control system is provided at an automatic transmission for selectively operating at least one operational element included in the powertrain depending on running states of a vehicle.
Such an automatic transmission includes a powertrain including a compound planetary gear set formed by combining at least two simple planetary gear sets to achieve required multiple speeds. A plurality of friction members and a hydraulic control system selectively operate the friction members of the powertrain depending on driving conditions. A friction member used for a powertrain of such automatic transmission may be a clutch or a brake, and the present invention generally relates to a wet type multiplate clutch.
As is generally known, the wet type multiplate clutch is configured such that a plurality of circular clutch plates and a plurality of circular clutch disks are alternately disposed in an axis direction and the clutch plate and the clutch disk are pressurized by a piston to generate friction therebetween, thereby transmitting power. In order to enhance torque capability, the number of the clutch plate and the clutch disk is generally increased. The increase of the number of clutch plates and clutch disks results in the drawback that a total length of an automatic transmission increases.
In Korean patent number 427665, a multipate clutch of an automatic transmission had been proposed which includes a plurality of clutch disks connected to a clutch hub. The combination rotates together with a transmission input shaft and is disposed around the transmission input shaft. A clutch plate is disposed between the clutch disks, formed as a cylindrical shape and divided into two portions, and performing a friction operation with the clutch disk while a diameter thereof is varied. A piston is installed to be movable in a radial direction of the transmission input shaft and pressurizes the clutch plate toward the clutch disk. Such multiplate clutch with a cylindrical shape may have wider friction surface thereby substantially increases torque transmission efficiency when compared to a conventional shaft direction disk type multiplate clutch. However, in such multiplate clutch, since the piston is disposed along a radial direction, there is a problem in that it is difficult to obtain sufficient hydraulic pressure supply passage. In addition, there is the drawback it is quite difficult to arrange the cylindrical clutch disk and plate to be movable in a radial direction.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.